There is very little that the NFL takes more seriously than espionage. For whatever reason, they do not want officials from the teams spying on players, coaches, and organizations of other teams. The Patriots were heavily fined and punished for Spygate. Former Denver coach Josh McDaniels was fired over Spygate II. Enter Spygate III. Saints GM Mickey Loomis is accused of having a device in his luxury box that allowed him to spy on opposing coaches.
Some GMs have a radio in their luxury suites or offices that allow them to listen in on their own coaches on the sideline. Apparently, Mickey Loomis is accused of having his radio rewired to listen in on not his own coaches, but opposing coaches. This lasted for his first three seasons with the team, from 2002-04, and the device was removed in 2005. He’d plug a headset into the jack on his desk and be able to monitor various communication devices used on the field and observe the operations of others. Granted, that might not be much of an advantage to a GM, but I imagine every little bit helps.